Regulating system



Feb. 14, 1939.

H. C. NYCUM REGULATING SYSTEM Filed Feb. 28, 1935 WITNESSES: V.

62 /Z A' l1 /4 [NVENTOR Patented Feb. 14, 1939 UNITED STATES PATENTOFFICE REGULATING SYSTEM Pennsylvania Application February 28, 1935,Serial No. 8,634

2 Claims.

matically comes into action if the basic or main control apparatusceases to function.

Another object is to simplify the apparatus and circuits required tomaintain forced vibration of the voltage-responsive control element.

A further object is to provide an improved method for compensating theregulator in accordance with changes in the loading of the regulatedmachine or circuit.

My invention itself, together with additional objects and advantagesthereof, will best be understood from a description of a specificembodiment when taken in conjunction with the accompanying drawing inwhich the single figure is a diagrammatic view of apparatus and circuitsillustrating the several improvements of my invention incorporated in agenerator voltage regulating system.

Referring to the drawing, the regulating system there illustrated isadapted to maintain constant the voltage of an alternating-currentgenerator in, the armature windings of which are directly connected tothe conductors I! of a three-phase power circuit. The field windings ofthe generator derives energizing current from a directcurrent exciterIS, the field winding I8 of which is self-excited through a circuitwhich includes a pair of resistors or rheostats and 22.

Normally, resistor 22 is bridged by the contact member 24 of a contactoror relay 26, while resistor 20 is intermittently bridged by the contactmember 28 of a second contactor or relay 3!) caused to rapidly open andclose under the controlling action of a voltage sensitive element 32.This element is energized by, a measure of the voltage of circuit l2through a pair of transformers 34 and 36 and a full wave rectifier 38.

I prefer to employ as the voltage-sensitive control element 32 astructure basically the same as that described in a patent to WalterSchaelchlin No. 1,820,712 granted August 25, 1931, and ascomprises amovable contact rnember 40, adapted to move between two stationarycontact members R and L, which is carried by a bell crank lever 42pivoted, at point 50, to a stationary or field member shown in the formof a tubular magnetizable portion 44 which is joined to one end of acore portion 46. The other end of this core extends, in the mannershown, back through the tubular portion 44'. The bell crank 42 carriesan insulating tube 48 which is disposed within the tubular field portion44 and around the corresponding portion of the core member 46 withouttouching either one. This bell crank is normally biased toward theright, tending to engage the contacts 40 and R by means of a spring 52.

In the field member 44-46 there is produced, by means of exciting coils54 and 56, a flux which operates substantially uniformly across the gapbetween the tubular portion 44 and that part of the core 46 which liestherewithin. This magnetic field is effective in producing a uniformmagnetic force which acts on the movable member with an intensity notvaried by the position of the movable member.

The two exciting windings 54 and 56 are series connected with each otherfor energization by the output of the previously mentioned rectifier 38which, in turn, is energized by a measure of the voltage of circuit l2.Winding 54 is wound on the insulating tube 48 attached to the bell crank42 and lies within the aforementioned uniform magnetic field whilewinding 56 is wound on that portion of the core member 46 lying outsideof the tubular frame portion 44 and thus produces the aforementionedfield.

The electromagnetic reactions between the movable and stationarywindings and this uniform air-gap field are such that magnetic pullproduced on the bell crank 42 tends to open the contacts 40 and R and toclose the contacts 40 and L against the pull of the biasing spring 52.

In the energizing circuit of the two exciting windings is connected aresistor 56 which, by virtue of a shunting connection establishedtherearound by means of relay 30, serves to maintain the contacts 40 andR in a state of continuous vibration during normal operation of theregulat ing system.

During such normal operation when the voltage of circuit|2 is of thedesired value the mag 'netic pull exerted by exciting windings 54 and 56of the voltage sensitive element 32 is, when the resistor 58 is in theenergizing circuit, insufiicient to overcome the tension of spring whichaccordingly biases movable contact member 4% into engagement withstationary member R. These contacts complete an actuating circuit forrelay 36 which extends from the positive terminal of the exciter l6,through conductors 60, 6| and 62, the relay winding 64, conductor 65,contact members R and Bi) of device 32 and conductor 66 back to thenegative terminal of exciter l6.

Thus energized relay 30 moves its contact member 28 upwardly therebyestablishing a shunt connection around excitation adjusting resistor 20by virtue of which connection the current supplied to the exciter fieldwinding I8 is raised. As a result the exciter voltage and hence theenergizing'current supplied to the field winding M of the regulatedmachine 10 starts to increase,

whichin turn causes the machine voltage to tend to rise.

In moving to the named actuated position, contact member 28 of relay 30also completes a shunting circuit around the resistor 58, therebyincreasing the current supplied to the windings 54 and 56 of device 32,which increase effects a separation of contact members 40 and R. Thisshunting circuit may be traced from the upper end of resistor 58 throughconductor 61, relay contact member 26, conductor 6i, a protective fuse12 and conductor 63 back to the lower end of resistor 58.

The named separation of contact members 40 and R deenergizes relay 30allowing contact member 28 to move downwardly to the unactuated positionshown. Such downward movement interrupts the shunt connection fromaround excitation-control resistor 20 and thereby reduces the currentsupplied to exciter field winding l8. By similarly interrupting theshunt connection from around resistor 58 the opening of contact member28 also decreases the current supplied to the exciting windings ofdevice 32. The resulting tendency for the voltage of regulated machineID to decrease is thus accompanied by a re-engagement of contact members40 and R and the cycle just described is caused to repeat itself at afrequency of several times per second.

Regulation of the voltage of machine I0 is, as in other vibratoryregulating systems, thus effected by varying the time-closed totime-opened periods of the control device contacts 40 and R, the valueof this ratio increasing when the machine voltage tends to fall belowthe desired value and decreasing when the opposite tendency is present.

One feature of my invention resides in the above-described scheme ofshunting the vibration-forcing resistor 58 by thesame contact member 28of relay 30 as functions in the main excitation control circuit. Thesimplicity of this arrangement constitutes a distinct advantage and ismade possible by interposing the rectifier 38 between the alternatingcurrent regulated circuit l2 and the voltage sensitive control element32. Such direct-current energization has the further advantage ofallowing the magnetic field which acts in the device 32 to beunidirectional, thereby improving contact operation and reduc ingchattering tendencies.

Adjustment in the value of voltage which the regulating system willmaintain may be effected by changing the setting of a voltage-adjustingrheostat 68 which may be placed at any convenient point in theenergizing circuit of de-. vice 32.

Considering now the disclosed stand-by regulating arrangement of myinvention, the need for this arises when, for any reason,excitation-controlling relay 30 fails to function in the manner desiredas for example, to reopen'the contact member 28 thereof. In such case,the tendency is for the regulated voltage to rise, since resistor 20 isthen continuously shunted from the excitation-supply circuit. Tocounteract this tendency, I provide the voltage-sensitive device 32 witha second stationary contact member L which when the voltage of circuitl2 hasrisen very slightly above the desired value is engaged by themovable member 40.

Such engagement completes an actuating circuit for the supplementalrelay 26 which extends from the positive terminal of exciter I6 throughconductors 60, 6| and 62, the relay winding 10, conductor II, thecontacts L and 40 of device 32 and conductor 66 back to' the negativeterminal of the exciter I6. Thus energized the relay 26 moves itscontact member 24 upwardly thereby interrupting the normally maintainedshunt circuit around resistor 22. The resulting insertion of thisresistor in the excitation supply circuit reduces the voltage of exciterl6 and hence checks the voltage rise of the regulated machine I0.

As a result of the decreased excitation the machine voltage may tend tofall below the desired value in which case device 32 will separatecontact member 40 from member L and thereby cause a re-establishmentthrough contact member 24 of relay 26 of the shunt connection aroundresistor 22. This again causes the machinevoltage to start to rise andthe cycle of operation just described continues to repeat itselfrapidly.

It will thus be seen by means of this simple stand-by regulatorequipment the voltage of the regulated machine is never permitted toappreciably rise above the desired value as it would were the stand-byequipment not to be provided. Inoperation the contact member 40 ofdevice 32 merely moves across the small gap between the two stationarymembers R and L. Thus this previously unused but simple combination ofad ditional main contacts and a spare relay permits the use of avibrating regulator with all its inherent advantages and with its chiefdisadvantage reduced to a minimum. As a further precaution, anyconventional form ofalarm system may be combined to indicate when thestand-by equipment has been brought into continuous op-' eration.

A further feature of my invention resides in the novel method ofcompensating the regulator for changes in machine loading. To effectthis compensation I provide upon the core 46 of the voltage sensitivedevice 32 an auxiliary winding 74 which, through a circuit whichincludes a potentiometer or voltage-dividing resistor 16, is energizedby a measure of the voltage appearing across the exciter field winding18. The disclosed parallel connection of thisresistor with the winding74 tends to equalize the fluctuations in the voltage supplied to windingl8 and cause its average value to influence the compensating winding 14.Furthermore, the inductive characteristics of this winding serve toadditionally smooth out the voltage fluctuations permitting in effectonly the average to modify the action of.

the control element 32.

The nature of this modification is such that as the energizing voltagesupplied to exciter winding l8 rises, as is the case when the output ofthe regulated machine i0 is increased, the device 32 will respond onlyto a higher value of machine voltage thereby producing the desiredrising voltage-with-machine-load characteristic. By adjusting theposition along resistor 16 of a tap connection 18, the degree of thisrising characteristic may be modified to suit operating conditions. Byreversing the connections of winding H a lowering-voltage-with-loadcharacteristic may similarly be produced.

If desired, the described excitation-responsive compensating means maybe supplemented by one which is directly responsive to the machineloading. Such is illustrated as comprising a resistor 80 connected inthe energizing circuit of voltage sensitive element 32 and adapted tohave circulated therethrough, by means of a current transformer 82, acurrent which is proportional to the output of the regulated machine l0.When the machine output increases the voltage drop across the resistor80 similarly rises and produces the desired form of compensation.Reversal of connections changes it to a 'lowering-with-load variety.

While I have shown and described certain specific embodimentsof myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the scope of theappended claims.

I claim as my invention:

1. In a regulator system, in combination, an electric generator, meansfor regulating an electric quantity responsive to the excitation of saidgenerator comprising a field winding circuit including a pair ofregulating resistors connected in series, a primary relay of thecontinuously vibrating type responsive to the regulatedquantity andhaving a movable contact member and a pair of fixed contact members,said relay be-' ing operative to cause intermittent engagement andseparation of said movable contact member with one only of said fixedcontact members to effect the intermittent shunting of one of saidcontrol resistors as the sole regulating resistor throughout thecomplete range of control of said field winding for controlling theregulated quantity within given limits and to cause intermittentengagement and separation of said movable contact member with the otherof said fixed contact members to efiect the intermittent shunting of theother of said control resistors as the sole regulating resistorthroughout the complete range of control of said field winding forcontrolling the regulated quantity within different limits.

2. In a regulator system, in combination, an electric generator, meansfor regulating an electric quantity that is responsive to the excitationof said generator comprising a field winding circuit including a pair ofregulating resistors connected in series, a secondary relay adapted toclose a circuit in shunt relation to one of said resistors and normallybiased to a circuit interrupting position, a secondary relay adapted toclose a circuit in shunt relation to the other of said resistors andnormally biased to a circuit closing position, a primary relay of thecontinuously vibrating type responsive to the regulated quantity forcontrolling the operation of said secondary relays, said primary relaybeing operative to effect the intermittent closing and opening of saidfirst-named secondary relay as the sole regulating element to vary theeffective value of its associated resistor throughout the complete rangeof control of the field winding when the second named secondary relay isin a circuit closing position, said primary relay being operative toeffect the intermittent closing and opening of said second-namedsecondary relay as the sole control element throughout the completerange of control of the field-winding when the first named secondaryrelay is in a circuit closing position.

HOMER C. NYCUM.

